The instant invention relates to a distortion-reducing mechanism for use with a projector. Specifically, the instant invention is a lens-angulation mechanism which facilitates inclination of a projection lens relative to a projector to eliminate distortion in a projected image.
Projectors, and specifically video projectors, may be used to display, on a large, generally planar screen, an image generated by a computer or by a television receiver. The projector is generally placed on a table or stand at some distance from a screen and the image is projected onto the screen. If the projector is placed on a stand at a level below the center of the screen, it is necessary to incline the projector upwards to center the image on the screen. This results in distortion in that the distance between the projector and the bottom of the image is less than the distance between the projector and the top of the image, with the result being that the top of the image is enlarged relative the bottom of the image.
One known technique to resolve this problem is to tilt the screen thereby aligning, in a parallel manner, the screen and the projector. Tilting the screen is not possible with most conventional projection screens, and screens which are tiltable are either provided in a permanent installation or are specialty items of considerable cost. Known projectors allow limited lens angulation.
An object of the instant invention is to provide a lens angulation mechanism which enables projection of a distortion-free image onto a planar projection screen when the projector is not aligned in a parallel manner with the projection screen.
Another object of the instant invention is to provide a lens angulation mechanism which rotatably and pivotally supports a projection lens and allows inclination in both a horizontal and vertical plane.
A further object of the instant invention is to provide a lens angulation mechanism which adjusts the inclination of the lens and positively holds the lens in an adjusted position.
Another object of the instant invention is to provide a lens angulation mechanism which is simple in construction and low in initial and maintenance costs.
Yet another object of the instant invention is to provide a lens angulation mechanism which is usable by one with little skill or instruction.
The instant invention includes a lens angulation mechanism comprising projection means having a frame and a projection lens with front and rear ends. Support means are operatively interposed between the lens and the frame. In the preferred embodiment, support means include a universal hinge having one element mounted adjacent the rear end of the lens and another element mounted on the frame. The term "universal" as used herein is intended to cover a hinge which is capable of movement in more than one plane. A ball and cup arrangement is normally provided for permitting movement along two perpendicular axes. Lens inclination adjustment means are also provided to positively adjust the inclination of the lens with respect to the frame and to positively locate the lens in an adjusted position.
These and other objects and advantages of the instant invention will become more fully apparent as the description which follows is read in conjunction with the drawings.